[FEATURE] Improve REDCapTidieR Execution Times

[rsh52]

Feature Request Description

REDCapTidieR runs slower than we'd like for larger databases where load times are more noticable.

Proposed Solution

It looks like one of the main culprits is a mutate/case_when used in create_repeat_vars which is a component of the add_partial_keys utility function:

We may want to lean on base R for this instead.

Another place of slow times is the multi_choice_to_labels function, though this may be more difficult to improve:

Checklist

• [x] The issue is atomic
• [x] The issue description is documented
• [x] The issue title describes the problem succinctly
• [x] Developers are assigned to the issue
• [x] Labels are assigned to the issue